Power Supply Unit and Operating Method Thereof

This application claims priority to Chinese Application Serial Number 202411528413.7, filed Oct. 30, 2024, which is herein incorporated by reference in its entirety.

The present disclosure relates to a power supply unit, and particularly relates to a power supply unit having a configurable output voltage.

At present, there are various power specifications of light-emitting diode (LED) lamps on the market, e.g., LED lamp strings connected in series and/or in parallel in a suitable form. In addition, LED lamps also have a variety of power specifications, e.g., LED lamps with an input voltage of 12V and LED lamps with an input voltage of 24V. In order to meet different power specifications of LED lamps, power supply unit manufacturers need to produce different models of power supply units, which not only increases the complexity of material preparation and manufacturing, but also brings inventory management problems, and even causes that lamp manufacturers may damage LED lamps due to the misuse of unsuitable specifications of power supplies.

As a result, an effective power supply unit design approach is required to solve the above technical problem. An aspect of the present disclosure is a power supply unit which supplies power to a load. The power supply unit comprises a power conversion circuit, an output control circuit, a current detection circuit, a first feedback circuit, a coupling circuit and a power conversion control circuit. The power conversion circuit comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal, the first input terminal and the second input terminal being configured to receive an input voltage, the first output terminal and the second output terminal being configured to be coupled to the load. The output control circuit is coupled to the first output terminal and has a control terminal. The current detection circuit comprises a first terminal coupled to the second output terminal of the power conversion circuit and a second terminal configured to be coupled to the load. The first feedback circuit is coupled to the first output terminal of the power conversion circuit to receive a first voltage detection signal, coupled to the current detection circuit to receive a first current detection signal, and coupled to the output control circuit to correspondingly generate a first control signal. The coupling circuit is coupled to the first feedback circuit to receive the first control signal and configured to generate a power conversion control signal based on the first control signal. The power conversion control circuit is coupled to the coupling circuit and the power conversion circuit and configured to generate a conversion signal based on the power conversion control signal. When the control terminal of the output control circuit is coupled to a first control voltage, the output control circuit sets the first control signal generated by the first feedback circuit, the first control signal sets the power conversion circuit to correspondingly generate a first output voltage, and the power conversion circuit has a first maximum output current. When the control terminal of the output control circuit is coupled to a second control voltage, the output control circuit sets the first control signal generated by the first feedback circuit, the first control signal sets the power conversion circuit to correspondingly generate a second output voltage, and the power conversion circuit has a second maximum output current. The first control voltage is greater than the second control voltage, the first output voltage is greater than the second output voltage, and the first maximum output current is less than the second maximum output current.

Another aspect of the present disclosure is an operating method of a power supply unit, which is configured to supply power to a load. The power supply unit comprises a power conversion circuit, an output control circuit, a current detection circuit, a first feedback circuit, a coupling circuit, and a power conversion control circuit. The power conversion circuit comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal, the first output terminal and the second output terminal being configured to be coupled to the load. The output control circuit is coupled to the first output terminal and has a control terminal. The current detection circuit comprises a first terminal coupled to the second output terminal of the power conversion circuit and a second terminal configured to be coupled to the load. The first feedback circuit is coupled to the first output terminal of the power conversion circuit, the current detection circuit and the output control circuit, the coupling circuit is coupled to the first feedback circuit, and the power conversion control circuit is coupled to the coupling circuit and the power conversion circuit. The operating method comprises: setting the first input terminal and the second input terminal of the power conversion circuit to receive an input voltage to supply, at the first output terminal and the second output terminal of the power conversion circuit, power to a load; setting the first feedback circuit to receive a first voltage detection signal from the first output terminal of the power conversion circuit and to receive a first current detection signal from the current detection circuit to correspondingly generate a first control signal; setting the coupling circuit to receive the first control signal from the first feedback circuit and to generate a power conversion control signal based on the first control signal; and setting the power conversion control circuit to generate a conversion signal based on the power conversion control signal. When the control terminal of the output control circuit is coupled to a first control voltage, the output control circuit sets the first feedback circuit to generate the first control signal, the first control signal sets the power conversion circuit to correspondingly generate a first output voltage, and the power conversion circuit has a first maximum output current. When the control terminal of the output control circuit is coupled to a second control voltage, the output control circuit sets the first feedback circuit to generate the first control signal, the first control signal sets the power conversion circuit to correspondingly generate a second output voltage, and the power conversion circuit has a second maximum output current. The first control voltage is greater than the second control voltage, the first output voltage is greater than the second output voltage, and the first maximum output current is less than the second maximum output current.

The power supply unit provided in the present disclosure can achieve a variety of power output specifications.

The following describes embodiments in detail with reference to the drawings. However, the specific embodiments described are only intended to illustrate the present disclosure, rather than to define the present disclosure, and the description on structure operations is not adopted to limit the order in which the structure operations are performed; and any device with an equal effect resulting from the recombination of components of the structure falls within the scope of the present disclosure.

Terms used throughout the Description and the Claims of the present disclosure, unless otherwise specified, generally have the ordinary meaning of each term used in the art, in the present disclosure and in special contents.

The term “coupling” used herein may refer to a direct physical or electrical contact between two or more components, or to an indirect physical or electrical contact between two or more components, or to an interoperation or action of two or more components.

1 FIG. 100 200 100 200 200 100 102 108 110 111 112 200 102 110 112 112 102 Reference is made towhich is a block diagram of an embodiment of a power supply unitconfigured to supply power to a load (LED), according to the present disclosure. The power supply unitis coupled to an anode LED(+) and a cathode LED(−) of the LEDto supply power to the LED. The power supply unitincludes a power conversion circuit, an output control circuit, a first feedback circuit, a coupling circuitand a power conversion control circuit. In one embodiment, the LEDmay include one or more light-emitting elements therein, and the power conversion circuitmay be a suitable power conversion architecture such as an isolated or non-isolated DC-DC converter, a SMPS (switch mode power supply) converter or an AC-DC converter. The first feedback circuitmay include elements such as a digital circuit, an analog circuit, an optocoupler and/or an optical isolator to transmit a feedback signal to the power conversion control circuit, so that the power conversion control circuitcan set the power conversion circuitto generate an appropriate output voltage Vout and/or an appropriate output current Iout.

108 100 200 200 100 108 In the following embodiment, through the control of a signal level of a control terminal CW of the output control circuit, the output voltage Vout of the power supply unitis controlled at 12V or 24V, so that the power supply unit correspondingly supplies power to the LEDwith a voltage of 12V or the LEDwith a voltage of 24V. In other embodiments, the output voltage Vout of the power supply unitmay also be set to be one of two or more other suitable voltages through the control of the signal level of the control terminal CW of the output control circuit.

102 108 110 1 111 1 1 111 112 1 112 102 102 a b In the present embodiment, the power conversion circuitcan be set to have both 12V and 24V power output specifications. When the control terminal CW is coupled to a first control voltage (e.g., high voltage), the output control circuitand the first feedback circuitgenerate and transmit a first control signal CSto the coupling circuitbased on the first control voltage, a first voltage detection signal Vand a first current detection signal V, the coupling circuitgenerates and transmits a power conversion control signal CS to the power conversion control circuitbased on the first control signal CS, and the power conversion control circuitgenerates and transmits a conversion signal Sc to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitperform a power conversion operation on a power input signal (that is, input voltage Vin) based on the conversion signal Sc to set the output voltage Vout to 24V.

108 110 1 111 1 1 111 112 1 112 102 102 a b When the control terminal CW is not coupled to the first control voltage (e.g., floated, grounded or coupled to a suitable voltage level such as a second control voltage less than the first control voltage), the output control circuitand the first feedback circuitgenerate and transmit the first control signal CSto the coupling circuitbased on the first voltage detection signal Vand the first current detection signal V, the coupling circuitgenerates and transmits the power conversion control signal CS to the power conversion control circuitbased on the first control signal CS, and the power conversion control circuitgenerates and transmits the conversion signal Sc to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitperform a power conversion operation on the input voltage Vin based on the conversion signal Sc to set the output voltage Vout to 12V.

102 102 102 102 102 102 102 102 102 200 1 200 102 200 a b c d a b c d c The power conversion circuitincludes a first input terminal, a second input terminal, a first output terminaland a second output terminal. The first input terminaland the second input terminalare configured to receive the input voltage Vin. The first output terminaland the second output terminalare configured to be coupled to the LEDto output a first voltage Vto the LED. The first output terminalis configured to be coupled to the anode LED(+) of the LED. The input voltage Vin can be an AC voltage or a DC voltage.

100 114 1 114 114 114 114 114 114 114 102 102 114 114 102 102 1 114 102 1 114 102 102 a b c d c d a b a b a b c a d b In one embodiment, the power supply unitfurther includes a power factor correction (PFC) circuitand a first capacitor C. The PFC circuitincludes a first AC input terminal, a second AC input terminal, a first PFC output terminaland a second PFC output terminal. The first PFC output terminaland the second PFC output terminalare coupled to the first input terminaland the second input terminalrespectively. The first AC input terminaland the second AC input terminalreceive an original voltage I/P to generate the input voltage Vin to the first input terminaland the second input terminal. A first terminal of the first capacitor Cis coupled to the first PFC output terminaland the first input terminal, and a second terminal of the first capacitor Cis coupled to the second PFC output terminaland the second input terminal. Therefore, through the above circuit structure, the power conversion circuitreceives the input voltage Vin. In one embodiment, the original voltage I/P may be an AC voltage.

100 114 1 102 102 102 a b In one embodiment, the power supply unitdoes not include the PFC circuitand the first capacitor C, and the first input terminaland the second input terminalof the power conversion circuitdirectly receive the original voltage I/P.

100 104 102 200 102 200 2 104 102 200 1 104 d c d b In the present embodiment, the power supply unitfurther includes a current detection circuitwhich is coupled to the second output terminaland the cathode LED(−) of the LED, and coupled to the first output terminaland the anode LED(+) of the LEDvia a second capacitor C. The current detection circuitincludes a first voltage across resistor Ra, a first terminal of the first voltage across resistor Ra is coupled to the second output terminal, and a second terminal of the first voltage across resistor Ra is coupled to the cathode LED(−) of the LED. Since voltage across both ends of the first voltage across resistor Ra is positively correlated with a current flowing through the first voltage across resistor Ra, a voltage value of the first voltage across resistor Ra can be used as the first current detection signal Vto detect a value of a current flowing through the current detection circuit.

108 102 110 108 100 102 108 108 100 108 c c The output control circuitis coupled to the first output terminaland the first feedback circuit. In one embodiment, if the control terminal CW of the output control circuitis to be coupled to the first control voltage so that the power supply unitgenerates an output voltage Vout of 24V, the control terminal CW can be coupled to the first output terminalso that the output control circuitoperates. If the control terminal CW of the output control circuitis to be not coupled to the first control voltage so that the power supply unitgenerates an output voltage Vout of 12V, the control terminal CW can be floated, grounded or coupled to a suitable voltage level such as the second control voltage less than the first control voltage, so that the output control circuitdoes not operate.

110 102 1 110 104 1 110 108 110 1 1 1 110 c a b a b A first terminal of the first feedback circuitis coupled to the first output terminalto receive the first voltage detection signal V, a second terminal of the first feedback circuitis coupled to the first voltage across resistance Ra of the current detection circuitto receive the first current detection signal V, and the first feedback circuitis further coupled to the output control circuit. The first feedback circuitcorrespondingly generates the first control signal CSbased on the first voltage detection signal Vand the first current detection signal Vand based on the operating state of the first feedback circuit.

100 2 2 200 In the present embodiment, the power supply unitfurther includes the second capacitor Cto provide a function of stabilizing the output voltage Vout. Both ends of the second capacitor Care coupled to the anode LED(+) and the cathode LED(−) of the LED, respectively.

111 110 1 1 The coupling circuitis coupled to the first feedback circuitto receive the first control signal CS, and configured to generate the power conversion control signal CS based on the first control signal CS.

112 110 The power conversion control circuitreceives the power conversion control signal CS generated by the first feedback circuitto generate the conversion signal Sc based on the power conversion control signal CS.

1 FIG. 102 112 112 As shown in, the power conversion circuitis coupled to the power conversion control circuit, and converts the input voltage Vin to the output voltage Vout at an appropriate voltage level based on the conversion signal Sc generated by the power conversion control circuit.

2 FIG.A 1 FIG. 2 FIG.A 100 102 108 110 112 Reference is made towhich is a block diagram showing some circuits of the power supply unitin. For illustrative purposes,shows only the power conversion circuit, the output control circuit, the first feedback circuit, and the power conversion control circuit.

2 FIG.A 108 108 108 108 108 108 108 108 108 a b a b a b a b As shown in the embodiment of, the output control circuitincludes the control terminal CW, a pin detecting circuitand a regulation generation circuit. The pin detecting circuitcorrespondingly sets the operating state of the regulation generation circuitbased on the voltage of the control terminal CW. When the control terminal CW is coupled to the first control voltage (e.g., high voltage), the pin detecting circuitsets the regulation generation circuitto operate; and when the control terminal CW is not coupled to the first control voltage (e.g., floated, grounded or coupled to a suitable voltage level such as the second control voltage less than the first control voltage), the pin detecting circuitsets the regulation generation circuitto not operate.

2 FIG.A 110 110 110 110 110 110 110 110 110 110 102 1 110 108 108 110 11 1 108 110 11 1 11 102 11 102 a b c d a c b d a c a a b b a a b a a As shown in the embodiment of, the first feedback circuitincludes a first voltage division circuit, a first voltage stabilizing circuit, a first comparison circuitand a second comparison circuit. The first voltage division circuitand the first comparison circuitprovide a voltage feedback control function, while the first voltage stabilizing circuitand the second comparison circuitprovide a current feedback control function. The first voltage division circuitis coupled to the first output terminalto receive the first voltage detection signal V, and the first voltage division circuitis coupled to the regulation generation circuit. When the regulation generation circuitdoes not operate, the first voltage division circuitgenerates a first voltage division control signal VPhaving a first level based on the first voltage detection signal V; and when the regulation generation circuitoperates, the first voltage division circuitgenerates the first voltage division control signal VPhaving a second level based on the first voltage detection signal V. In one embodiment, the first voltage division control signal VPhaving the first level corresponds to the output voltage Vout (12V) of the power conversion circuit, and the first voltage division control signal VPhaving the second level corresponds to the output voltage Vout (24V) of the power conversion circuit.

100 110 108 108 12 110 102 108 12 110 102 b b b b b b In one embodiment, the power supply unitcan be set to provide two power specifications, i.e., an output voltage of 12V and a maximum output current of 5 A (maximum output power of 60 W) and an output voltage of 24V and a maximum output current of 2.5 A (maximum output power of 60 W). The first voltage stabilizing circuitis coupled to the regulation generation circuit. When the regulation generation circuitdoes not operate, a first current division control signal VPhaving a third level generated by the first voltage stabilizing circuitcorresponds to the maximum output current Iout of the power conversion circuit, which is 5 A. When the regulation generation circuitoperates, the first current division control signal VPhaving a fourth level generated by the first voltage stabilizing circuitcorresponds to the maximum output current Iout of the power conversion circuit, which is 2.5 A.

110 110 11 11 11 102 11 102 c a The first comparison circuitis coupled to the first voltage division circuit, and configured to compare the first voltage division control signal VPwith a reference voltage signal Vref to generate a first voltage control signal Shaving a fifth or sixth level respectively. In one embodiment, the first voltage control signal Shaving the fifth level corresponds to the output voltage Vout of the power conversion circuit, which is 12V, and the first voltage control signal Shaving the sixth level corresponds to the output voltage Vout of the power conversion circuit, which is 24V.

110 110 12 1 12 12 102 12 102 1 11 12 d b b The second comparison circuitis coupled to the first voltage stabilizing circuit, and configured to compare the first current division control signal VPwith the first current detection signal Vto generate a first current control signal Shaving a seventh or eighth level, respectively. In one embodiment, the first current control signal Shaving the seventh level corresponds to the maximum output current Iout of the power conversion circuit, which is 5 A, and the first current control signal Shaving the eighth level corresponds to the maximum output current Iout of the power conversion circuit, which is 2.5 A. In the present embodiment, the first control signal CSconsists of the first voltage control signal Sand the first current control signal S.

The first level to the eighth level can be set to the same or different signal levels respectively.

111 110 110 1 c d The coupling circuitis coupled to the first comparison circuitand the second comparison circuit, and correspondingly generates the power conversion control signal CS based on the first control signal CS.

2 FIG.B 2 FIG.A 2 FIG.B 100 108 1 2 1 11 1 2 3 4 5 6 108 3 4 7 8 1 3 4 2 1 a b Reference is made towhich is a specific circuit architecture diagram of the power supply unitin. As shown in the embodiment of, the pin detecting circuitincludes a first switch Q, a second switch Q, a first diode D, a third capacitor C, a first resistor R, a second resistor R, a third resistor R, a fourth resistor R, a fifth resistor R, and a sixth resistor R. The regulation generation circuitincludes a third switch Q, a fourth switch Q, a seventh resistor R, and an eighth resistor R. In one embodiment, the first switch Q, the third switch Qand the fourth switch Qmay each be an N-channel MOSFET, the second switch Qmay be a PNP bipolar junction transistor (BJT), and the first diode Dmay be a Zener diode.

1 1 2 11 1 2 1 1 1 2 1 2 11 1 2 1 1 11 1 1 3 102 102 1 4 3 4 1 1 2 3 4 2 102 102 1 5 2 6 5 6 c c The first diode D, the first resistor R, the second resistor Rand the third capacitor Care configured to convert the voltage of the control terminal CW to a suitable voltage level, so that the first switch Qand the second switch Qare in an on or off state. A cathode LED(−) of the first diode Dis coupled to the control terminal CW. A first terminal of the first resistor Ris coupled to an anode LED(+) of the first diode D. A first terminal of the second resistor Ris coupled to a second terminal of the first resistor R, and a second terminal of the second resistor Ris grounded. A first terminal of the third capacitor Cis coupled to the second terminal of the first resistor R, the first terminal of the second resistor Rand a gate gof the first switch Q, and a second terminal of the third capacitor Cis grounded. A source sof the first switch Qis grounded. A first terminal of the third resistor Ris coupled to the first output terminalof the power conversion circuitto receive the first voltage V. A first terminal of the fourth resistor Ris coupled to a second terminal of the third resistor R, and a second terminal of the fourth resistor Ris coupled to a drain dof the first switch Q. A base B of the second switch Qis coupled to the second terminal of the third resistor Rand the first terminal of the fourth resistor R, and an emitter E of the second switch Qis coupled to the first output terminalof the power conversion circuitto receive the first voltage V. A first terminal of the fifth resistor Ris coupled to a collector C of the second switch Q. A first terminal of the sixth resistor Ris coupled to a second terminal of the fifth resistor R, and a second terminal of the sixth resistor Ris grounded.

3 3 5 6 3 3 7 110 7 3 3 4 4 3 3 5 6 4 4 8 110 8 4 4 A gate gof the third switch Qis coupled to the second terminal of the fifth resistor Rand the first terminal of the sixth resistor R, and a source sof the third switch Qis grounded. A first terminal of the seventh resistor Ris coupled to the first feedback circuit, and a second terminal of the seventh resistor Ris coupled to a drain dof the third switch Q. A gate gof the fourth switch Qis coupled to the gate gof the third switch Q, the second terminal of the fifth resistor Rand the first terminal of the sixth resistor R, and a source sof the fourth switch Qis coupled to ground. A first terminal of the eighth resistor Ris coupled to the first feedback circuit, and a second terminal of the eighth resistor Ris coupled to a drain dof the fourth switch Q.

1 2 108 3 4 108 1 2 108 3 4 108 a b a b When the control terminal CW is coupled to the first control voltage, the first switch Qand the second switch Qof the pin detecting circuitare switched on, so that the third switch Qand the fourth switch Qof the regulation generation circuitare switched on. When the control terminal CW is not coupled to the first control voltage (e.g., floated, grounded or coupled to a suitable voltage level such as the second control voltage less than the first control voltage), the first switch Qand the second switch Qof the pin detecting circuitare not switched on, so that the third switch Qand the fourth switch Qof the regulation generation circuitare not switched on.

2 FIG.B 110 9 10 11 12 13 110 13 16 110 2 14 15 12 1 110 3 17 18 14 2 111 1 110 112 111 110 110 1 112 a b c d c d As shown in the embodiment of, the first voltage division circuitincludes a ninth resistor R, a tenth resistor R, an eleventh resistor R, a twelfth resistor R, and a thirteenth resistor R. The first voltage stabilizing circuitincludes a fifth capacitor Cand a sixteenth resistor R. The first comparison circuitincludes a second diode D, a fourteenth resistor R, a fifteenth resistor R, a fourth capacitor C, and a first operational amplifier OP. The second comparison circuitincludes a third diode D, a seventeenth resistor R, an eighteenth resistor R, a sixth capacitor C, and a second operational amplifier OP. The coupling circuitmay transmit the first control signal CSof the first feedback circuitto the power conversion control circuitin an appropriate signal transmission mode, e.g., an electrical signal, an optical signal, a magnetic signal, or the like. In one embodiment, the coupling circuitincludes a photodiode and a photodetector, the photodiode is coupled to the first comparison circuitand the second comparison circuitto convert the first control signal CSto an optical signal, and the photodetector receives the optical signal and converts the optical signal to the power conversion control signal CS for transmission to the power conversion control circuit.

9 1 10 9 11 10 11 12 1 13 12 13 1 9 10 1 12 13 1 102 102 1 14 1 12 14 12 1 1 15 12 1 1 2 15 16 10 11 13 16 13 2 16 13 2 1 2 102 102 2 17 2 14 17 14 2 2 18 14 2 2 3 18 3 2 a a c b c A first terminal of the ninth resistor Rreceives the first voltage detection signal V. A first terminal of the tenth resistor Ris coupled to a second terminal of the ninth resistor Rto receive the reference voltage signal Vref. A first terminal of the eleventh resistor Ris coupled to a second terminal of the tenth resistor R, and a second terminal of the eleventh resistor Ris grounded. A first terminal of the twelfth resistor Rreceives the first voltage detection signal V. A first terminal of the thirteenth resistor Ris coupled to a second terminal of the twelfth resistor R, and a second terminal of the thirteenth resistor Ris grounded. A non-inverting input terminal (+) of the first operational amplifier OPis coupled to the second terminal of the ninth resistor Rand the first terminal of the tenth resistor Rto receive the reference voltage signal Vref, and an inverting input terminal (−) of the first operational amplifier OPis coupled to the second terminal of the twelfth resistor Rand the first terminal of the thirteenth resistor R, a positive power terminal Vs+ of the first operational amplifier OPis coupled to the first output terminalof the power conversion circuit, and a negative power terminal Vs− of the first operational amplifier OPis grounded. A first terminal of the fourteenth resistor Ris coupled to the inverting input (−) of the first operational amplifier OP. A first terminal of the fourth capacitor Cis coupled to a second terminal of the fourteenth resistor R, and a second terminal of the fourth capacitor Cis coupled to a first amplification output terminal Voof the first operational amplifier OP. A first terminal of the fifteenth resistor Ris coupled to the second terminal of the fourth capacitor Cand the first amplification output terminal Voof the first operational amplifier OP. A first terminal of the second diode Dis coupled to a second terminal of the fifteenth resistor R. A first terminal of the sixteenth resistor Ris coupled to the second terminal of the tenth resistor Rand the first terminal of the eleventh resistor R. A first terminal of the fifth capacitor Cis coupled to a second terminal of the sixteenth resistor R, and a second terminal of the fifth capacitor Cis grounded. An non-inverting input terminal (+) of the second operational amplifier OPis coupled to the second terminal of the sixteenth resistor Rand the first terminal of the fifth capacitor C, an inverting input terminal (−) of the second operational amplifier OPreceives the first current detection signal V, a positive power terminal Vs+ of the second operational amplifier OPis coupled to the first output terminalof the power conversion circuit, and a negative power terminal Vs− of the second operational amplifier OPis grounded. A first terminal of the seventeenth resistor Ris coupled to the inverting input terminal (−) of the second operational amplifier OP. A first terminal of the sixth capacitor Cis coupled to a second terminal of the seventeenth resistor R, and a second terminal of the sixth capacitor Cis coupled to a second amplification output terminal Voof the second operational amplifier OP. A first terminal of the eighteenth resistor Ris coupled to the second terminal of the sixth capacitor Cand the second amplification output terminal Voof the second operational amplifier OP. A first terminal of the third diode Dis coupled to a second terminal of the eighteenth resistor R, and a second terminal of the third diode Dis coupled to a second terminal of the second diode D.

1 10 11 1 In one embodiment, the reference voltage signal Vref may be a reference voltage signal generated by a constant-voltage voltage source, e.g., a voltage of 2.5V. The reference voltage signal Vref generates a first reference voltage division signal Vrefthrough the voltage division of the tenth resistor Rand the eleventh resistor R, and the voltage of the first reference voltage division signal Vrefis

112 111 102 A first terminal of the power conversion control circuitis coupled to the coupling circuitto receive the power conversion control signal CS and generates the conversion signal Sc based on the power conversion control signal CS to control the power conversion circuitto generate the desired output voltage Vout.

2 FIG.B 102 102 1 2 1 2 As shown in the embodiment of, the power conversion circuitincludes a SMPS converterX, a first winding N, and a second winding N. In one embodiment, the first winding Nis a primary side winding or a primary coil, and the second winding Nis a secondary side winding or a secondary coil.

102 102 102 102 1 102 2 200 102 2 200 a b c d First and second terminals of the SMPS converterX (i.e., first input terminaland second input terminal) receive the input voltage Vin. Third and fourth terminals of the SMPS converterX are coupled to first and second terminals of the first winding N. A first terminal (i.e., first output terminal) of the second winding Nis configured to be coupled to the anode LED(+) of the LED. A second terminal (i.e., second output terminal) of the second winding Nis configured to be coupled to the cathode LED(−) of the LED.

108 108 110 11 11 110 12 1 12 1 11 12 111 112 1 112 102 102 a b c d b Therefore, when the control terminal CW is not coupled to the first control voltage (e.g., high voltage), the pin detecting circuitand the regulation generation circuitdo not operate, the first comparison circuitcorrespondingly generates the first voltage control signal Sbased on the first voltage division control signal VPand the reference voltage signal Vref, and the second comparison circuitcompares the first current division control signal VPwith the first current detection signal Vto correspondingly generate the first current control signal S. The first control signal CSincludes the first voltage control signal Sand the first current control signal Swhich are used as feedback signals of voltage feedback control and current feedback control, respectively. The coupling circuitgenerates the power conversion control signal CS to the power conversion control circuitbased on the first control signal CS, and the power conversion control circuitgenerates the conversion signal Sc to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitgenerates an output voltage Vout of 12V based on the conversion signal Sc, and controls the maximum output current Iout to be 5 A.

2 FIG.B 1 1 2 108 108 3 4 108 1 1 11 a a b a As shown in the embodiment of, when the control terminal CW is not coupled to the first control voltage (e.g., high voltage), the first diode D, the first switch Qand the second switch Qof the pin detecting circuitare not switched on, so that the pin detecting circuitdoes not operate and correspondingly controls the third switch Qand the fourth switch Qof the regulation generation circuitto not be switched on. The first voltage detection signal Vgenerates, at the inverting input terminal (−) of the first operational amplifier OP, the first voltage division control signal VP

12 13 1 11 11 16 1 12 2 12 1 12 b corresponding to the output voltage Vout of 12V through the voltage division of the twelfth resistor Rand the thirteenth resistor R, the first operational amplifier OPcompares the first voltage division control signal VPwith the reference voltage signal Vref to generate the first voltage control signal Scorresponding to the output voltage Vout of 12V, and the sixteenth resistor Rreceives the first reference voltage division signal Vrefto generate the first current division control signal VP, and the second operational amplifier OPcompares the first current division control signal VPwith the first current detection signal Vto generate the first current control signal S.

1 1 1 1 1 2 1 1 1 2 108 108 1 2 2 5 6 2 3 4 3 4 108 3 7 13 7 13 1 1 11 1 1 111 1 112 102 1 11 a a b a When the control terminal CW is coupled to the first control voltage (e.g., high voltage), the first control voltage is greater than a breakdown voltage of the first diode Dso that the first diode Dis switched on, a voltage obtained by subtracting the breakdown voltage of the first diode Dfrom the first control voltage is formed into a first partial voltage VPthrough the voltage division of the first resistor Rand the second resistor R, the first partial voltage VPis greater than a threshold voltage of the first switch Qso that the first switch Qand the second switch Qare switched on and then the pin detecting circuitoperates. By the operation of the pin detecting circuit, the first voltage V, after subtracting a voltage drop of the second switch Q, is formed into a second partial voltage VPthrough the voltage division of the fifth resistor Rand the sixth resistor R, and the second partial voltage VPis greater than a threshold voltage of the third switch Qand the fourth switch Qso that the third switch Qand the fourth switch Qcan be switched on, and then the regulation generation circuitoperates. After the third switch Qis switched on, the seventh resistor Ris connected in parallel to the thirteenth resistor R, and a resistance value of the seventh resistor Rconnected in parallel to the thirteenth resistor Rdecreases, resulting in a voltage drop at the inverting input terminal (−) of the first operational amplifier OP. Since a voltage at the non-inverting input terminal (+) of the first operational amplifier OPis still the reference voltage signal Vref, the first voltage control signal Sgenerated by the first operational amplifier OP, the first control signal CS, the power conversion control signal CS generated by the coupling circuitbased on the first control signal CS, and the conversion signal Sc generated by the power conversion control circuitbased on the power conversion control signal CS will cause the power conversion circuitto correspondingly raise the output voltage Vout based on the conversion signal Sc, so that the first voltage detection signal Vrises to that the first voltage division control signal VP

4 8 11 8 11 2 12 2 1 111 1 112 102 1 12 b is equal to reference voltage signal Vref. In the present embodiment, the output voltage Vout at this time is 24V. Similarly, after the fourth switch Qis switched on, the eighth resistor Ris connected in parallel to the eleventh resistor R, and a resistance value of the eighth resistor Rconnected in parallel to the eleventh resistor Rdecreases, resulting in a voltage drop at the non-inverting input terminal (+) of the second operational amplifier OP. The first current control signal Sgenerated by the second operational amplifier OP, the first control signal CS, the power conversion control signal CS generated by the coupling circuitbased on the first control signal CS, and the conversion signal Sc generated by the power conversion control circuitbased on the power conversion control signal CS will cause the power conversion circuitto correspondingly reduce the output current Iout based on the conversion signal Sc, so that the first current detection signal Vdecreases to be equal to the first current division control signal VP. In the present embodiment, the maximum output current Iout at this time is 2.5 A.

2 FIG.B 1 1 1 1 1 1 2 1 1 As shown in the embodiment of, when the control terminal CW is coupled to the first control voltage, the first diode Dis switched on, and the first voltage V, after subtracting a voltage across the first diode D, is applied at the gate gof the first switch Qthrough the voltage division of the first resistor Rand the second resistor Rto generate the first partial voltage VPto switch on the first switch Q.

1 1 1 1 2 3 4 2 1 2 2 1 1 2 3 3 4 4 5 6 2 2 When the first partial voltage VPis greater than the threshold voltage of the first switch Q(e.g., 3.5V), the first switch Qis switched on, and the first voltage Vis applied at the base B of the second switch Qthrough the voltage division of the third resistor Rand the fourth resistor R, so that the second switch Qis switched on, and then the first voltage Vis transmitted to the collector C of the second switch Q(since the voltage drop of the second switch Qis much less than the first voltage V, and is thus negligible). The first voltage Vof the collector C of the second switch Qis applied at the gate gof the third switch Qand the gate gof the fourth switch Qthrough the voltage division of the fifth resistor Rand the sixth resistor Rto generate the second partial voltage VP(i.e., detection signal). In one embodiment, the second partial pressure VPis approximately

2 3 4 3 4 3 7 13 1 1 1 12 7 13 11 1 11 11 4 8 11 2 2 12 10 8 11 2 12 1 12 11 12 1 111 111 112 1 112 102 102 a b When the second partial voltage VPis greater than the threshold voltage of the third switch Qand the fourth switch Q(e.g., 3.5V), the third switch Qand the fourth switch Qare switched on. After the third switch Qis switched on, the seventh resistor Ris connected in parallel to the thirteenth resistor Rto set the voltage level of the inverting input terminal (−) of the first operational amplifier OP, the first voltage detection signal Vis generated at the inverting input terminal (−) of the first operational amplifier OPthrough the voltage division of the twelfth resistor R, the seventh resistor Rand the thirteenth resistor Rto generate the first voltage division control signal VPcorresponding to the output voltage Vout of 24V, and the first operational amplifier OPcompares the first voltage division control signal VPwith the reference voltage signal Vref to generate the first voltage control signal Scorresponding to the output voltage Vout of 24V. After the fourth switch Qis switched on, the eighth resistor Ris coupled in parallel to the eleventh resistor Rto set the voltage level of the non-inverting input terminal (+) of the second operational amplifier OP, the reference voltage signal Vref generates, at the non-inverting input terminal (+) of the second operational amplifier OP, the first current division control signal VPcorresponding to the maximum output current Iout of 2.5 A through the voltage division of the tenth resistor R, the eighth resistor Rand the eleventh resistor R, the second operational amplifier OPcompares the first current division control signal VPwith the first current detection signal Vto generate the first current control signal Scorresponding to the maximum output current Iout of 2.5 A, the first voltage control signal Sand the first current control signal Sform the first control signal CScorresponding to an output voltage Vout of 24V and a maximum output current Iout of 2.5 A to the coupling circuit, the coupling circuitgenerates the power conversion control signal CS corresponding to an output voltage Vout of 24V and a maximum output current Iout of 2.5 A to the power conversion control circuitbased on the first control signal CS, and the power conversion control circuitgenerates the conversion signal Sc corresponding to an output voltage Vout of 24V and a maximum output current Iout of 2.5 A to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitgenerates the output voltage Vout of 24V from the input voltage Vin based on the conversion signal Sc and controls the maximum output current Iout to be 2.5 A.

108 110 100 2 100 100 As a result, through the output control circuitand a single-loop control circuit (i.e., first feedback circuit) of the power supply unitin FIGS. 1 and 2 A-B, the control terminal CW can be selectively coupled to the first control voltage (e.g., high voltage) to control the output voltage Vout of the power supply unitto be 12V or 24V, so that the power supply unitcan achieve the required power output specification of 12V or 24V based on the setting.

3 FIG. 1 FIG. 3 FIG. 1 FIG. 3 FIG. 1 FIG. 100 100 200 102 112 114 1 2 is a block diagram of another embodiment of a power supply unit according to the present disclosure. Referring toand, the power supply unitinand a power supply unit′ inhave a partially similar circuit structure, both of which are configured to supply power to the LEDand have the power conversion circuit, the power conversion control circuit, the PFC circuit, the first capacitor C, and the second capacitor C. The technical disclosure related toare not repeated.

108 100 100 200 200 100 108 In the following embodiment, through the control of a signal level of a control terminal CW of an output control circuit′, an output voltage Vout of the power supply unit′ is controlled to be 12V or 24V, so that the power supply unit′ correspondingly supplies power to the LEDwith a voltage of 12V or the LEDwith a voltage of 24V. In other embodiments, the output voltage Vout of the power supply unit′ may also be set to one of two or more other suitable voltages through the control of the signal level of the control terminal CW of the output control circuit′.

102 108 110 2 108 110 1 110 2 110 1 2 111 1 1 2 2 111 112 1 2 112 102 102 a b a b In the present embodiment, the power conversion circuitcan be set to have both 12V60 W and 24V100 W power output specifications. When the control terminal CW is coupled to a first control voltage (e.g., high voltage), the output control circuit′ sets a second feedback circuit_to operate correspondingly. The output control circuit′ and a first feedback circuit_and the second feedback circuit_of a feedback circuit′ generate and transmit the first control signal CSand the second control signal CSto the coupling circuitbased on the first voltage detection signal V, the first current detection signal V, the second voltage detection signal Vand the second current detection signal V, the coupling circuitgenerates and transmits the power conversion control signal CS to the power conversion control circuitbased on the first control signal CSand the second control signal CS, and the power conversion control circuitgenerates and transmits the conversion signal Sc to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitperforms a power conversion operation on a power input signal (i.e., input voltage Vin) based on the conversion signal Sc to set the output voltage Vout to 24V and control the maximum output current at 4.1 A, so that the maximum output power is set to 100 W.

108 110 2 108 110 1 110 1 111 1 1 111 112 1 112 102 102 a b When the control terminal CW is not coupled to the first control voltage (e.g., grounded or floated), the output control circuit′ sets the second feedback circuit_to correspondingly not operate. The output control circuit′ and the first feedback circuit_of the feedback circuit′ generate and transmit the first control signal CSto the coupling circuitbased on the first voltage detection signal Vand the first current detection signal V, the coupling circuitgenerates and transmits the power conversion control signal CS to the power conversion control circuitbased on the first control signal CS, and the power conversion control circuitgenerates and transmits the conversion signal Sc to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitperforms a power conversion operation on the input voltage Vin based on the conversion signal Sc to set the output voltage Vout to 12V and control the maximum output current at 5 A, so that the maximum output power is set to 60 W.

3 FIG. 100 104 As shown in, the power supply unit′ includes a current detection circuit′.

104 200 102 200 2 1 2 104 c b b The current detection circuit′ includes a first voltage across resistor Ra and a second voltage across resistor Rb, a first terminal of the second voltage across resistor Rb is coupled to a second terminal of the first voltage across resistor Ra, and a second terminal of the second voltage across resistor Rb is coupled to the cathode LED(−) of the LED, and coupled to the first output terminaland the anode LED(+) of the LEDthrough the second capacitor C. Since the voltages of the first voltage across resistor Ra and the second voltage across resistor Rb are positively correlated with the currents flowing through the first voltage across resistor Ra and the second voltage across resistor Rb respectively, the voltage values of the first voltage across resistor Ra and the second voltage across resistor Rb can be taken as the first current detection signal Vand the second current detection signal V, respectively, to detect a value of a current flowing through the current detection circuit′.

3 FIG. 100 108 102 110 c As shown in, the power supply unit′ includes an output control circuit′ coupled to the first output terminaland a feedback circuit′.

3 FIG. 1 FIG. 1 FIG. 100 110 110 1 110 2 110 1 110 110 1 As shown in, the power supply unit′ includes the feedback circuit′ including the first feedback circuit_and the second feedback circuit_. In one embodiment, the first feedback circuit_has a circuit structure similar to that of the first feedback circuitin, so the technical disclosure of the first feedback circuit_related tois not detailed.

3 FIG. 1 FIG. 110 2 102 2 110 2 104 200 2 110 2 108 1 110 2 2 2 2 108 1 110 2 110 110 1 2 1 2 c a b a b a b As shown in the embodiment of, a first terminal of the second feedback circuit_is coupled to the first output terminalto receive the second voltage detection signal V, and a second terminal of the second feedback circuit_is coupled to a current detection circuit′ and the cathode LED(−) of the LEDto receive the second current detection signal V. The second feedback circuit_is further coupled to the output control circuit′ to selectively receive the first voltage V. The second feedback circuit_correspondingly generates the second control signal CSbased on the second voltage detection signal Vand the second current detection signal Vand based on the setting of the output control circuit′ (i.e., whether the first voltage Vis received). In one embodiment, the second feedback circuit_has a circuit structure similar to those of the first feedback circuitinand the first feedback circuit_, the second voltage detection signal Vis equal to or close to the voltage value of the first voltage V, and the second current detection signal Vis a voltage value at the second voltage across resistor Rb.

111 110 1 110 2 1 2 1 2 The coupling circuitis coupled to the first feedback circuit_and the second feedback circuit_to receive the first control signal CSand the second control signal CS, and configured to generate the power conversion control signal CS based on the first control signal CSand the second control signal CS.

112 111 102 112 112 The power conversion control circuitis coupled to the coupling circuitand configured to generate the conversion signal Sc based on the power conversion control signal CS. The power conversion circuitis coupled to the power conversion control circuit, and converts the input voltage Vin to the output voltage Vout having an appropriate voltage level based on the conversion signal Sc generated by the power conversion control circuit.

4 FIG.A 3 FIG. 4 FIG.A 2 4 FIGS.A andA 2 4 FIGS.A andA 2 FIG.A 4 FIG.A 2 FIG.A 4 FIG.A 2 FIG.A 100 102 108 110 1 110 2 111 112 102 112 108 108 110 110 110 110 110 110 1 110 1 110 1 110 1 110 1 a b c d a b c d is a block diagram showing some circuits of the power supply unit′ in. For illustrative purposes,shows only the power conversion circuit, the output control circuit′, the first feedback circuit_, the second feedback circuit_, the coupling circuit, and the power conversion control circuit. Referring to, since the power conversion circuitand the power conversion control circuitin, the output control circuitinand the output control circuit′ in, the first feedback circuitin(including the first voltage division circuit, the first voltage stabilizing circuit, the first comparison circuitand the second comparison circuit), and the first feedback circuit_in(including a first voltage division circuit_, a first voltage stabilizing circuit_, a first comparison circuit_and a second comparison circuit_) have the same or similar circuit structures, the technical disclosures related towill not be repeated.

4 FIG.A 108 108 1 110 2 110 2 1 108 108 1 110 2 110 2 1 a b a b As shown in, when the control terminal CW is coupled to the first control voltage (e.g., high voltage), the pin detecting circuitsets the regulation generation circuitto operate, and provides the first voltage Vto the second feedback circuit_as the working voltage, so that the second feedback circuit_receives the first voltage Vand operates; and when the control terminal CW is not coupled to the first control voltage (e.g., floated, grounded or coupled to a suitable voltage level such as a second control voltage less than the first control voltage), the pin detecting circuitsets the regulation generation circuitto not operate, and does not provide the first voltage Vto the second feedback circuit_as the working voltage, so that the second feedback circuit_does not receive the first voltage Vand does not operate.

4 FIG.A 4 FIG.A 100 110 1 110 2 110 2 110 1 110 2 110 2 110 2 110 2 110 2 110 2 110 2 110 2 110 2 110 2 102 2 110 2 21 2 110 2 110 2 2 2 22 110 2 110 2 108 108 1 110 2 110 2 108 1 110 2 110 2 21 21 110 2 110 2 108 108 1 110 2 110 2 108 1 110 2 110 2 22 22 2 2 21 22 21 21 102 22 22 102 a b c d a c b d a c a a a b a a a c a a a c c a c c d b a a d d a d d b As shown in, the power supply unit′ includes the first feedback circuit_and the second feedback circuit_. In one embodiment, the second feedback circuit_has a circuit structure similar to that of the first feedback circuit_. In one embodiment, as shown in, the second feedback circuit_includes a second voltage division circuit_, a second voltage stabilizing circuit_, a third comparison circuit_, and a fourth comparison circuit_. The second voltage division circuit_and the third comparison circuit_provide a voltage feedback control function, while the second voltage stabilizing circuit_and the fourth comparison circuit_provide a current feedback control function. The second voltage division circuit_is coupled to the first output terminalto receive the second voltage detection signal V, and the second voltage division circuit_generates a second voltage division control signal VPbased on the second voltage detection signal V. The second voltage stabilizing circuit_is coupled to the second voltage division circuit_to receive a partial voltage of the second voltage detection signal V, and the partial voltage of the second voltage detection signal Vis used as a second current division control signal VP. The third comparison circuit_is coupled to the second voltage division circuit_and the pin detecting circuit; when the pin detecting circuitdoes not provide the first voltage Vto the third comparison circuit_, the third comparison circuit_does not operate; and when the pin detecting circuitprovides the first voltage Vto the third comparison circuit_, the third comparison circuit_operates and is configured to generate a second voltage control signal Sbased on the second voltage division control signal VP. The fourth comparison circuit_is coupled to the second voltage stabilizing circuit_and the pin detecting circuit; when the pin detecting circuitdoes not provide the first voltage Vto the fourth comparison circuit_, the fourth comparison circuit_does not operate; and when the pin detecting circuitprovides the first voltage Vto the fourth comparison circuit_, the fourth comparison circuit_operates and is configured to generate a second current control signal Sbased on the second current division control signal VPand the second current detection signal V. In one embodiment, the second control signal CSconsists of the second voltage control signal Sand the second current control signal S. In one embodiment, the second voltage division control signal VPand the second voltage control signal Scorrespond to the output voltage Vout of the power conversion circuit, which is 24V, and the second current division control signal VPand the second current control signal Scorrespond to the output current Iout of the power conversion circuit, which is 4.1 A.

4 FIG.A 111 110 1 110 1 110 2 110 2 1 2 1 2 c d c d As shown in the embodiment in, the coupling circuitis coupled to the first comparison circuit_, the second comparison circuit_, the third comparison circuit_and the fourth comparison circuit_to receive the first control signal CSand the second control signal CS, so as to generate the power conversion control signal CS based on the first control signal CSand the second control signal CS.

4 FIG.B 4 FIG.A 2 FIG.B 4 FIG.B 2 FIG.B 4 FIG.B 2 FIG.B 100 108 108 a b Reference is made towhich is a specific circuit architecture diagram of the power supply unit′ in. Referring toand, since the pin detecting circuitsand the regulation generation circuitsinandhave the same or similar circuit structure, the technical disclosure related tois not repeated.

2 FIG.B 4 FIG.B 4 FIG.B 2 FIG.B 2 FIG.B 110 1 110 1 110 1 110 1 110 110 110 110 a b c d a b c d Referring toand, since the circuit structures of the first voltage division circuit_, the first voltage stabilizing circuit_, the first comparison circuit_and the second comparison circuit_inare the same or similar to those of the first voltage division circuit, the first voltage stabilizing circuit, the first comparison circuitand the second comparison circuitin, the technical disclosures related toare not repeated.

4 FIG.B 110 2 19 20 21 22 23 110 2 16 26 110 2 4 15 22 25 3 110 2 5 17 27 28 4 111 1 110 1 2 110 2 112 111 110 1 110 1 110 2 110 2 1 2 112 a b c d c d c d As shown in the embodiment of, the second voltage division circuit_includes a nineteenth resistor R, a twentieth resistor R, a twenty-first resistor R, a twenty-second resistor Rand a twenty-third resistor R, the second voltage stabilizing circuit_includes an eighth capacitor Cand a twenty-sixth resistor R, the third comparison circuit_includes a fourth diode D, a seventh capacitor C, a twenty-fourth resistor R, a twenty-fifth resistor Rand a third operational amplifier OP, and the fourth comparison circuit_includes a fifth diode D, a ninth capacitor C, a twenty-seventh resistor R, a twenty-eighth resistor R, and a fourth operational amplifier OP. The coupling circuitmay transmit the first control signal CSof the first feedback circuit_and the second control signal CSof the second feedback circuit_to the power conversion control circuitin an appropriate signal transmission mode, e.g., an electrical signal, an optical signal, a magnetic signal, or the like. In one embodiment, the coupling circuitincludes a photodiode and a photodetector. The photodiode is coupled to the first comparison circuit_, the second comparison circuit_, the third comparison circuit_and the fourth comparison circuit_to convert the first control signal CSand the second control signal CSto an optical signal, and the photodetector receives the optical signal and converts the optical signal to the power conversion control signal CS for transmission to the power conversion control circuit.

19 2 20 19 21 20 21 22 2 23 22 23 3 19 20 3 22 23 3 2 3 22 3 15 22 15 3 3 25 15 3 3 4 25 26 20 21 16 26 16 4 26 16 4 2 4 3 2 4 27 4 17 27 17 4 4 28 17 4 4 5 28 5 4 a a b A first terminal of the nineteenth resistor Rreceives the second voltage detection signal V. A first terminal of the twentieth resistor Ris coupled to a second terminal of the nineteenth resistor Rto receive the reference voltage signal Vref. A first terminal of the twenty-first resistor Ris coupled to a second terminal of the twentieth resistor R, and a second terminal of twenty-first resistor Ris grounded. A first terminal of the twenty-second resistor Rreceives the second voltage detection signal V. A first terminal of the twenty-third resistor Ris coupled to a second terminal of the twenty-second resistor R, and a second terminal of the twenty-third resistor Ris grounded. A non-inverting input terminal (+) of the third operational amplifier OPis coupled to the second terminal of the nineteenth resistor Rand the first terminal of the twentieth resistor Rto receive the reference voltage signal Vref, and an inverting input terminal (−) of the third operational amplifier OPis coupled to the second terminal of the twenty-second resistor Rand the first terminal of the twenty-third resistor R, a positive power terminal Vs+ of the third operational amplifier OPis coupled to a collector C of the second switch Q, and a negative power terminal Vs− of the third operational amplifier OPis grounded. A first terminal of the twenty-fourth resistor Ris coupled to the inverting input terminal (−) of the third operational amplifier OP. A first terminal of the seventh capacitor Cis coupled to the second terminal of the twenty-fourth resistor R, and a second terminal of the seventh capacitor Cis coupled to a third amplification output terminal Voof the third operational amplifier OP. A first terminal of the twenty-fifth resistor Ris coupled to the second terminal of the seventh capacitor Cand the third amplification output terminal Voof the third operational amplifier OP. A first terminal of the fourth diode Dis coupled to a second terminal of the twenty-fifth resistor R. A first terminal of the twenty-sixth resistor Ris coupled to the second terminal of the twentieth resistor Rand the first terminal of the twenty-first resistor R. A first terminal of the eighth capacitor Cis coupled to a second terminal of the twenty-sixth resistor R, and a second terminal of the eighth capacitor Cis grounded. A non-inverting input terminal (+) of the fourth operational amplifier OPis coupled to the second terminal of the twenty-sixth resistor Rand the first terminal of the eighth capacitor C, an inverting input terminal (−) of the fourth operational amplifier OPreceives the second current detection signal V, a positive power terminal Vs+ of the fourth operational amplifier OPis coupled to the positive power terminal Vs+ of the third operational amplifier OPand the collector C of the second switch Q, and a negative power terminal Vs− of the fourth operational amplifier OPis grounded. A first terminal of the twenty-seventh resistor Ris coupled to the inverting input terminal (−) of the fourth operational amplifier OP. A first terminal of the ninth capacitor Cis coupled to a second terminal of the twenty-seventh resistor R, and a second terminal of the ninth capacitor Cis coupled to a fourth amplification output terminal Voof the fourth operational amplifier OP. A first terminal of the twenty-eighth resistor Ris coupled to the second terminal of the ninth capacitor Cand the fourth amplification output terminal Voof the fourth operational amplifier OP. A first terminal of the fifth diode Dis coupled to a second terminal of the twenty-eighth resistor R, and a second terminal of the fifth diode Dis coupled to a second terminal of the fourth diode D.

13 23 23 7 13 11 21 21 8 11 In one embodiment, the thirteenth resistor Ris greater than the twenty-third resistor R, and a resistance value of the twenty-third resistor Ris substantially equal to that of the seventh resistor Rconnected in parallel to the thirteenth resistor R. The eleventh resistor Ris greater than the twenty-first resistor R, and a resistance value of the twenty-first resistor Ris essentially equal to that of the eighth resistor Rconnected in parallel to the eleventh resistor R.

2 20 21 2 In one embodiment, the reference voltage signal Vref generates a second reference voltage division signal Vrefthrough the voltage division of the twentieth resistor Rand the twenty-first resistor R, and the voltage of the second reference voltage division signal Vrefis

2 wherein the second reference voltage division signal Vrefis substantially equal to the first reference voltage division signal

108 108 110 2 110 1 1 1 11 a b a Therefore, when the control terminal CW is not coupled to the first control voltage (e.g., high voltage), the pin detecting circuit, the regulation generation circuitand the second feedback circuit_do not operate. In the first feedback circuit_, the first voltage detection signal Vgenerates, at the inverting input terminal (−) of the first operational amplifier OP, the first voltage division control signal VP

12 13 1 11 11 16 1 12 2 12 1 12 110 1 11 11 110 1 12 1 12 1 11 12 111 112 1 112 102 102 b c d b corresponding to the output voltage Vout of 12V through the voltage division of the twelfth resistor Rand the thirteenth resistor R, the first operational amplifier OPcompares the first voltage division control signal VPwith the reference voltage signal Vref to generate the first voltage control signal Scorresponding to the output voltage Vout of 12V, the sixteenth resistor Rreceives the first reference voltage division signal Vrefto generate the first current division control signal VP, and the second operational amplifier OPcompares the first current division control signal VPwith the first current detection signal Vto generate the first current control signal S. As a result, the first comparison circuit_correspondingly generates the first voltage control signal Sbased on the first voltage division control signal VPand the reference voltage signal Vref, and the second comparison circuit_compares the first current division control signal VPwith the first current detection signal Vto correspondingly generate the first current control signal S. The first control signal CSincludes the first voltage control signal Sand the first current control signal Swhich are used as feedback signals of voltage feedback control and current feedback control, respectively. The coupling circuitgenerates the power conversion control signal CS to the power conversion control circuitbased on the first control signal CS, and the power conversion control circuitgenerates the conversion signal Sc to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitgenerates an output voltage Vout of 12V based on the conversion signal Sc, and controls the maximum output current Iout to be 5 A.

4 FIG.B 1 1 2 108 108 3 4 108 1 3 4 3 4 1 110 2 110 2 100 108 1 110 2 110 2 a a b c d As shown in the embodiment of, when the control terminal CW is not coupled to the first control voltage (e.g., high voltage), the first diode D, the first switch Qand the second switch Qof the pin detecting circuitare not switched on, so that the pin detecting circuitdoes not operate to correspondingly control the third switch Qand the fourth switch Qof the regulation generation circuitto be not switched on, and will not provide the first voltage Vto the third operational amplifier OPand the fourth operational amplifier OP. The third operational amplifier OPand the fourth operational amplifier OPdo not receive the first voltage Vso that the third comparison circuit_and the fourth comparison circuit_do not operate, respectively. When the control terminal CW of the power supply unit′ is not coupled to the first control voltage (e.g., high voltage), the output control circuitwill not supply the first voltage Vto the second feedback circuit_, so that the second feedback circuit_does not operate.

1 1 1 1 1 2 1 1 1 2 108 108 1 2 2 5 6 2 3 4 3 4 108 108 1 110 2 110 2 2 110 2 110 2 3 7 13 7 13 1 1 3 11 1 21 3 1 2 111 1 2 112 102 1 a a b a c d c d a When the control terminal CW is coupled to the first control voltage (e.g., high voltage), the first control voltage is greater than the breakdown voltage of the first diode Dso that the first diode Dis switched on, the voltage obtained by subtracting the breakdown voltage of the first diode Dfrom the first control voltage is formed into the first partial voltage VPthrough the voltage division of the first resistor Rand the second resistor R, wherein the first partial voltage VPis greater than the threshold voltage of the first switch Qso that the first switch Qand the second switch Qare switched on and then the pin detecting circuitoperates. By the operation of the pin detecting circuit, the first voltage V, after subtracting a voltage drop of the second switch Q, is formed into a second partial voltage VPthrough the voltage division of the fifth resistor Rand the sixth resistor R, and the second partial voltage VPis greater than the threshold voltage of the third switch Qand the fourth switch Qso that the third switch Qand the fourth switch Qcan be switched on, and then the regulation generation circuitoperates. In addition, by the operation of the pin detecting circuit, the first voltage Vis transmitted to the third comparison circuit_and the fourth comparison circuit_due to the second switch Qbeing switched on, so that the third comparison circuit_and the fourth comparison circuit_operate. After the third switch Qis switched on, the seventh resistor Ris connected in parallel to the thirteenth resistor R, and a resistance value of the seventh resistor Rconnected in parallel to the thirteenth resistor Rdecreases, resulting in a voltage drop at the inverting input terminal (−) of the first operational amplifier OP. Since the voltages at the non-invert input terminals (+) of the first operational amplifier OPand the third operational amplifier OPare still the reference voltage signal Vref, the first voltage control signal Sgenerated by the first operational amplifier OP, the second voltage control signal Sgenerated by the third operational amplifier OP, the first control signal CS, the second control signal CS, the power conversion control signal CS generated by the coupling circuitbased on the first control signal CSand the second control signal CS, and the conversion signal Sc generated by the power conversion control circuitbased on the power conversion control signal CS will cause the power conversion circuitto correspondingly raise the output voltage Vout based on the conversion signal Sc, so that the first voltage detection signal Vrises to that the first voltage division control signal VP

4 8 11 8 11 2 12 2 22 4 1 2 111 1 2 112 102 1 12 b is equal to the reference voltage signal Vref. In the present embodiment, the output voltage Vout at this time is 24V. Similarly, after the fourth switch Qis switched on, the eighth resistor Ris connected in parallel to the eleventh resistor R, and a resistance value of the eighth resistor Rconnected in parallel to the eleventh resistor Rdecreases, resulting in a voltage drop at the non-inverting input terminal (+) of the second operational amplifier OP. The first current control signal Sgenerated by the second operational amplifier OP, the second current control signal Sgenerated by the fourth operational amplifier OP, the first control signal CS, the second control signal CS, the power conversion control signal CS generated by the coupling circuitbased on the first control signal CSand the second control signal CS, and the conversion signal Sc generated by the power conversion control circuitbased on the power conversion control signal CS will cause the power conversion circuitto correspondingly reduce the output current Iout based on the conversion signal Sc, so that the first current detection signal Vdecreases to be equal to the first current division control signal VP. In the present embodiment, the maximum output current Iout at this time is 4.1 A.

2 3 22 23 21 3 21 21 2 26 20 21 26 2 22 4 4 22 2 22 21 22 2 111 111 112 1 2 112 102 102 a b The second voltage detection signal Vis generated at the inverting input terminal (−) of the third operational amplifier OPthrough the voltage division of the twenty-second resistor Rand the twenty-third resistor Rto form the second voltage division control signal VPcorresponding to an output voltage Vout of 24V, and the third operational amplifier OPcompares the second voltage division control signal VPwith the reference voltage signal Vref to generate the second voltage control signal Scorresponding to an output voltage Vout of 24V. The reference voltage signal Vref generates the second reference voltage partial signal Vrefto the twenty-sixth resistor Rthrough the voltage division of the twentieth resistor Rand the twenty-first resistor R, the twenty-sixth resistor Rgenerates, based on the second reference voltage division signal Vref, the second current division control signal VPcorresponding to a maximum output current Iout of 4.1 A at the non-inverting input terminal (+) of the fourth operational amplifier OP, the fourth operational amplifier OPcompares the second current division control signal VPwith the second current detection signal Vto generate the second current control signal Scorresponding to a maximum output current Iout of 4.1 A, the second voltage control signal Sand the second current control signal Sform the second control signal CScorresponding to an output voltage Vout of 24V and a maximum output current Iout of 4.1 A to the coupling circuit, the coupling circuitgenerates the power conversion control signal CS corresponding to an output voltage Vout of 24V and a maximum output current Iout of 4.1 A to the power conversion control circuitbased on the first control signal CSand the second control signal CS, and the power conversion control circuitgenerates the conversion signal Sc corresponding to an output voltage Vout of 24V and a maximum output current Iout of 4.1 A to the power conversion circuitbased on the power conversion control signal CS, so that the power conversion circuitgenerates the output voltage Vout of 24V from the input voltage Vin based on the conversion signal Sc and controls the maximum output current Iout to be 4.1 A.

Based on a maximum output power of the power supply unit, the power supply unit needs to meet the requirements of corresponding safety specifications. In terms of the above embodiments, when the output power of the power supply unit is 60 W, a single feedback circuit can be used. When the output power of the power supply unit is 100 W, two feedback circuits must be used, and when any one of the two feedback circuits fails, the power supply unit still can operate normally by the single feedback circuit, so the power supply unit can meet safety specifications (e.g., UL 8750 Class 2 safety specification) through the redundant feedback circuit design.

100 100 100 Thus, the power supply units,′ in the above embodiments, whether using a single feedback circuit or two or more feedback circuits with the redundant design, can achieve different output voltages by selectively coupling the control terminal CW to the first control voltage (e.g., high voltage) to control the output voltage Vout of the power supply unit′ to be 12V or 24V, set the output currents correspondingly to provide different output powers, and achieve a constant voltage control function and/or a constant current control function.

Although the present disclosure has been disclosed as above in embodiments, the embodiments are not intended to limit the present disclosure. Those having ordinary skill in the technical field to which the present disclosure pertains may make various changes and embellishments without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be defined in the attached claims.